The present invention relates to a process for conditioning contaminated ion-exchange resins, and more particularly to the conditioning of contaminated cationic resins. The process of the invention applies in general manner to the conditioning of mixtures of cationic and anionic resins.
The ion-exchange resins which it is desired to condition by the present process are polystyrene resins cross-linked with divinylbenzene having either sulphonic SO.sub.3 H groups (cationic resins) or OH functions fixed to a quaternary ammonium group (anionic resins).
French Patent Application EN 73 4005 filed on Nov. 9, 1973 by the present Applicant describes a process for conditioning ion-exchange resins which have been used for the purification of contaminated water. It is known that ion-exchange resins used for purifying contaminated water, particularly water from moderators, are subject to degradation phenomena after a certain time and consequently lose their effectiveness. It is then a question of conditioning these spent ion-exchange resins. However, during use these resins fix a certain number of radioelements which give them a certain radioactivity. According to the process described in French Application EN 73 4005, said ion-exchange resins are incorporated into a resin which is polymerisable at ambient temperature, and the polymerisation of the latter is then brought about to obtain a solid block.
However, the process of French Application EN 73 4005 has a disadvantage when the ion-exchange resins which it is desired to condition are cationic resins which are not completely spent. In this case it has been found that the polymerisation of the resin used for covering the ion-exchange resins does not take place in a complete manner.
The Applicant has performed research in this connection and has found that the reason why the polymerisation of the resin used to coat the ion-exchange resins is incomplete is due to the presence of active sites still contained in a not completely spent cationic resin. In other words, the H.sup.+ protons contained in such a cationic resin consume certain of the compounds added to the polymerisable resin, more particularly the accelerator and thus retard polymerisation.